Tunable Biogenic Manganese Oxides.

Influence of the conditions for aerobic oxidation of Mn2+(aq) catalysed by the MnxEFG protein complex on the morphology, structure and reactivity of the resulting biogenic manganese oxides (MnOx ) is explored. Physical characterisation of MnOx includes scanning and transmission electron microscopy, and X-ray photoelectron and K-edge Mn, Fe X-ray absorption spectroscopy. This characterisation reveals that the MnOx materials share the structural features of birnessite, yet differ in the degree of structural disorder. Importantly, these biogenic products exhibit strikingly different morphologies that can be easily controlled. Changing the substrate-to-protein ratio produces MnOx either as nm-thin sheets, or rods with diameters below 20 nm, or a combination of the two. Mineralisation in solutions that contain Fe2+(aq) makes solids with significant disorder in the structure, while the presence of Ca2+(aq) facilitates formation of more ordered materials. The (photo)oxidation and (photo)electrocatalytic capacity of the MnOx minerals is examined and correlated with their structural properties.

Simple fabrication of zeolitic imidazolate framework ZIF-8/polymer composite beads by phase inversion method for efficient oil sorption.

Zeolitic imidazolate framework ZIF-8 beads of 2-3mm in diameter were prepared using a simple one-step phase inversion method. The beads were fabricated by different amounts of ZIF-8 to polyether sulfone (PES) ratios. ZIF-8 played the role of an adsorbent while PES acted as a binder in the composite matrix to keep the ZIF-8 particles. Since ZIF-8 is highly hydrophobic, the beads floated on water and adsorbed oil droplets successfully. This efficient oil adsorption is attributed to the hydrophobicity and high surface area of ZIF-8 particles which can effectively adsorb oil droplets. Different characterization techniques were used to understand the textural properties of the composite beads. The FESEM analysis showed that ZIF-8 particles were well coated and dispersed into the polymer bead composites and some pores are created on the beads surface at higher loadings which facilitated high oil sorption. The nitrogen adsorption-desorption indicated that ZIF-8/PES beads had very high surface area which makes them suitable for adsorption applications. The ZIF-8/PES beads demonstrate easy handling and recycling compared to ZIF-8 powder and showed superior buoyancy and oil sorption capacity compared with natural sorbents like activated carbon. This study shows the phase inversion method can be applied to produce a variety of functional composite bead materials for specific applications like adsorption.

Solar Water Oxidation by Multicomponent TaON Photoanodes Functionalized with Nickel Oxide.

Efficient solar-powered water oxidation over the TaON-based anodes requires coupling this photoactive n-type semiconductor to an electrooxidation catalyst to improve the otherwise unsatisfactory activity and stability. Herein, we examine how functionalization with electrodeposited nickel oxide, NiOx , affects the performance of screen-printed TaON photoanodes post-necked with titania (TiO2 -TaON). The effects of the NiOx photo-electrodeposition parameters on the microstructure and photocatalytic performance of the resulting anodes are explored. Enhancements in the transient water oxidation photocurrent densities by sixfold vs. unmodified TiO2 -TaON were achieved with the use of the NiOx /TiO2 -TaON photoanodes. Long-term stability tests reveal a slow but persistent degradation of the performance of the multicomponent photocatalysts under the severely oxidizing conditions of water photo-oxidation coincident with continuous morphological changes in the NiOx deposits.

Electrosynthesis of highly transparent cobalt oxide water oxidation catalyst films from cobalt aminopolycarboxylate complexes.

Efficient catalysis of water oxidation represents one of the major challenges en route to efficient sunlight-driven water splitting. Cobalt oxides (CoOx ) have been widely investigated as water oxidation catalysts, although the incorporation of these materials into photoelectrochemical devices has been hindered by a lack of transparency. Herein, the electrosynthesis of transparent CoOx catalyst films is described by utilizing cobalt(II) aminopolycarboxylate complexes as precursors to the oxide. These complexes allow control over the deposition rate and morphology to enable the production of thin, catalytic CoOx films on a conductive substrate, which can be exploited in integrated photoelectrochemical devices. Notably, under a bias of 1.0 V (vs. Ag/AgCl), the film deposited from [Co(NTA)(OH2 )2 ](-) (NTA=nitrilotriacetate) decreased the transmission by only 10 % at λ=500 nm, but still generated >80 % of the water oxidation current produced by a [Co(OH2 )6 ](2+) -derived oxide film whose transmission was only 40 % at λ=500 nm.

In vitro enzymatic degradation of poly (glycerol sebacate)-based materials.

Enzymatic degradation is a major feature of polyester implants in vivo. An in vitro experimental protocol that can simulate and predict the in vivo enzymatic degradation kinetics of implants is of importance not only to our understanding of the scientific issue, but also to the well-being of animals. In this study, we explored the enzymatic degradation of PGS-based materials in vitro, in tissue culture medium or a buffer solution at the pH optima and under static or cyclic mechanical-loading conditions, in the presence of defined concentrations of an esterase. Surprisingly, it was found that the in vitro enzymatic degradation rates of the PGS-based materials were higher in the tissue culture medium than in the buffered solution at the optimum pH 8. The in vitro enzymatic degradation rate of PGS-based biomaterials crosslinked at 125°C for 2 days was approximately 0.6-0.9 mm/month in tissue culture medium, which falls within the range of in vivo degradation rates (0.2-1.5mm/month) of PGS crosslinked at similar conditions. Enzymatic degradation was also further enhanced in relation to mechanical deformation. Hence, in vitro enzymatic degradation of PGS materials conducted in tissue culture medium under appropriate enzymatic conditions can quantitatively capture the features of in vivo degradation of PGS-based materials and can be used to indicate effective strategies for tuning the degradation rates of this material system prior to animal model testing.